Radiation triggered internal combustion engine ignition system



Oct. 29, 1968 L. R. HETZLER RADIATION TRIGGERED INTERNAL COMBUSTION ENGINE IGNITION SYSTEM Filed Sept.

2 Sheets-Sheet 1 Fig. I

' INVENTOR. Lew/s R. He/z/er His Attorney United States Patent 3,407,796 2 RADIATION TRIGGERED INTERNAL COMBUS- TION ENGINE IGNITION SYSTEM Lewis R. Hetzler, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware 7 Filed Sept. 22, 1966, Ser. No. 581,286 2 Claims. (Cl. 123-148) ABSTRACT OF THE DISCLOSURE to shaft speed to control the effective opening coupling the source of radioactive energy and the switching device and at least one of the disks is adjustable relative to the shaft to provide a centrifugal advance for the ignition system.

This invention relates to an ignition system for an internal combusition engine and more particularly to an ignition system wherein the application of power to the spark plug of the internal combustion engine is controlled by a device which is sensitive to radioactive energy.

One of the objects of this invention is to provide an ignition system for an internal combustion engine where a device which is sensitive to radioactive energy controls the application of power to thespark plugs of the engine and where a source of radioactive energy is employed to sequentially cause the device to operate in accordance with the crank shaft position of the engine.

Still another object of this invention is to provide an ignition system for an internal combustion engine where a radioactive device controls the energizing circuit for the primary winding of an ignition coil and where a source of radioactive energy is aligned with the radioactive device and further where an element driven in synchronism with the engine is disposed between the source of radioactive energy and the radioactive device to control the application of energy to the device in synchronism with operation of the engine.

Still another object of this invention is to provide an ignition system of the type described wherein two control members are disposed between the source of radioactive energy and the radioactive switching device and where one of the control members is shifted relative to a driving shaft as a function of shaft speed and where the other member is shifted such that the angle of engine rotation during which the primary Winding is energized isreduced ,as engine speed increases. With this device, a centrifugal advance is provided and an arrangement is provided which varies the angle through which the ignition coil is energized in accordance with engine speed. This is advantageous since during high speed operation of the engine, a conventional system provides less time to energize the primary winding of the ignition coil between successive firings of the spark plugs. When using the arrangement of this invention, the time available to energize the ignition coil can be maintained essentially constant as engine speed increases.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein prer 4 3,407,796 Patented Oct. 29, 1968 ferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 illustrates an ignition system made in accordance with this invention where the control device is shown in an exploded view.

FIGURE 2 is a sectional view of a control device made in accordance with this invention.

Referring now to the drawings and more particularly to FIGURE 1, the reference numeral 10 designates an internal combustion engine having a spark plug 12. Although only one spark plug is illustrated, it will be appreciated by those skilled in the art that as many spark plugs will be provided as there are cylinders in the engine.

The spark plug 12 is energized from a conductor 14 which is connected in a conventional manner with a secondary winding 16 of an ignition coil 18. In the drawing, the secondary winding 16 is shown directly connected to the spark plug 12 but as will be appreciated by those skilled in the art, this connection is made through distributor cap electrodes and a rotatable rotor as will be more fully described hereinafter.

The ignition coil 18 has a primary winding 20 and it is seen that this winding and the secondary winding 16 are connected together and to ground. The primary winding 20 is energized from conductor 22 which is connected with a control device 24 that is sensitive to radioactive energy. The control device 24 has another terminal connected with conductor 26 and this conductor is connected to one side of a source of direct current 28 which is illustrated as a battery. One side of the battery 28 is grounded as shown. It will be appreciated that where the system is used on a vehicle having a generator for charging the battery, that the generator can be used as a source of direct current for energizing the ignition system as is known to those skilled in the art.

The device 24 which is sensitive to radioactive energy preferably takes the form of a semiconductor switch which when exposed to radiation will become conductive and will therefore electrically connect the conductors 22 and 26. Thus when the semiconductor device 24 is exposed to radiation, the primary winding 20 will be energized from battery 28, through conductor 26, through the conductive semiconductor device 24, through lead wire 22, and then through primary winding 20 to ground. When the semiconductor switch 24 is not exposed to radiation, it becomes nonconductive to effectively disconnect wires 22 and 26. When this happens, the circuit to the primary winding 20 is opened and a voltage is induced in the secondary winding 16 which is applied to the spark plug 12 to provide a spark for igniting the combustible mixture of the engine.

Although the semiconductor switch 24 has been shown directly controlling the circuit for the primary winding 20, it will be appreciated by those skilled in the art that this device could be used to control the conduction of other variable conducting elements which would be connected to control primary Winding current. Thus, it is possible for the semiconductor switch 24 to control another semiconductor such as a transistor which then directly controls primary winding current.

It is also contemplated that the semiconductor switch 24 can be part of a capacitor discharge type of ignition system where the semiconductor switch 24 controls the discharging of a capacitor either through the primary winding of an ignition coil or directly through a spark plug.

The control device for controlling the application of radioactive energy to the semiconductor switch 24 will now be described. This control device as seen in FIG- URES 1 and 2 includes a base 30 that rotatably supports a shaft 32. The shaft 32 is driven in synchronism with the crank shaft of the internal combustion engine and the position of the shaft 32 therefore is an indication of piston position of the internal combustion engine.

A timing plate designated by reference numeral 34 is adjustable relative to the shaft 32 and carries the semiconductor switch 24. The timing plate 34 can be connected with a conventional vacuum unit 36 which is connected with the intake manifold of the engine 10 and adjusts the timing plate 34 in a manner well-known to those skilled in the art.

The source of radioactive energy which actuates the semiconductor switch 24 is designated by reference numeral 38 and is carried by a support 46 which is connected to the timing plate 34. The source of radioactive energy 38 is aligned with the semiconductor switch 24 so that when there is nothing in the path between the source and the semiconductor switch, the semiconductor switch is actuated to a conductive condition.

The arrangement for controlling the application of radioactive energy to the semiconductor switch 24 includes a pair of control disks 42 and 44 which respectively have radially extending arms 42a and 44a. The control disk 42 is driven by the shaft 32 through a centrifugal advance mechanism generally designated by reference numeral 46. This centrifugal advance mechanism is shown schematically in FIGURE 1 and is shown in the sectional view of FIGURE 2. This mechanism includes a plate 48 connected to the shaft 32 and a pair of flyweights 50 and 52 journalled on pins 54 and 56. The pins 54 and 56 are secured to the control disk 42 and the arrangement is such that the flyweights 50 and 52 have cam surfaces engaging cam surfaces formed on plate 48 to adjust the control disk 42 relative to shaft 32 as a function of engine speed. This centrifugal advance mechanism includes the usual springs 58 connecting pins 60 respectively with pins 54 and 56. The particular centrifugal advance mechanism just described is conventional and is more fully illustrated in U.S. Patent No. 3,250,867, issued on May 10, 1966, and assigned to the assignee of this invention. It will, of course, be appreciated that in a conventional centrifugal advance arrangement for a distributor, the centrifugal advance arrangement adjusts a cam rather than a control disk such as control disk 42.

The control disk 42 is connected with a bushing 62 which is disposed around the shaft 32 and which drives the plate 64 of another centrifugal advance mechanism generally designated by reference numeral 66. The centrifugal advance mechanism 66 has the same elements as the centrifugal advance mechanism 46 and is operative to adjust the control disk 44 relative to disk 42 and to shaft 32. In this regard, it is noted that the control disk 44 is secured to a bushing 68 which is journalled for rotation on the shaft 32.

As the shaft 32 is driven by the engine 10, the controlling disks 42 and 44 rotate therewith and the arms 42a and 44a of the control disks rotate between the aligned source of radiation 38 and the semiconductor switch 24. When there is an open path between the source of radiation 38 and the semiconductor switch 24, it will be conductive but when this path is blocked by the arms of the control disks, the semiconductor switch 24 will be nonconductive. The control disk-s 42 and 44 and the centrifugal advance mechanisms 46 and 66 are arranged such that the arms 42a overlap the arms 44a so that the angle of rotation of the engine through which the semiconductor switch 24 is activated depends upon the circumferential spacing between the overlapped arms of the control disks 42 and 44. The centrifugal advance mechanism 66 will adjust the control disk 44 relative to control disk 42 to control the amount of overlap between the arms of the control disks 42 and 44. When the arms 42a are exactly aligned with the arms 44a, the semiconductor switch will be activated for a longer period of time since there now is a 4 maximum open area between the arms of the control disks.

The arrangement is such that as shaft speed increases, the effective open area provided by the teeth of the two disks is increased so that the semiconductor switch 24 is actuated over a greater angle of rotation of the engine. As the speed of shaft 32 decreases, the control disk 44 moves in such a direction as to reduce the elfective open area between the source 38 and the device 24 to therefore reduce the angle of rotation of the engine through which the switch 24 is actuated. 1

It will, of course, be appreciated that a centrifugal advance is provided in this system by the control disk 42 and the control disk 44 serves to provide a current saving feature for this system since it reduces the shaft angle of rotation of the engine through which the semiconductor switch 24 is conductive at low speeds of the engine. If it were not for the control disk 44, the open area between the source 38 and the semiconductor switch 24 would be the constant open area between the teeth 42a. By using the control disk 44, however, it is possible to vary the effective open area to provide an arrangement where current is conserved at low engine speeds.

The control device illustrated in FIGURE 2 includes a conventional distributor cap 70 having a center electrode 72 and a plurality of circumferentially spaced electrodes 74. The electrodes 74 are connected respectively to the spark plugs 12 of the engine 10 while the center electrode 72 is connected with the secondary winding 16. The connection between the center electrode 72 and the outer electrode 74 is provided by a rotor contact 76 carried by an insulator 78 that is driven by the control disk 42.

While the embodiments of the present invention as herein disclosed constitute a preferred form, it is to be understood that other forms might be adapted.

What is claimed is as follows:

1. An ignition control unit for controlling the ignition system of an internal combustion engine comprising; a source of radioactive energy, a switching device responsive to said source of energy, a shaft adapted to be rotatably driven by an engine, and first and second rotor elements each having radially extending arms defining spaces between the arms rotatably driven by said shaft, said rotor elements adjustable relative to each other and positioned to swing between said source of radioactive energy and said switching device as said rotor elements are driven by said shaft, said rotor elements controlling the coupling of said source of radioactive energy and said switching device in synchronism with rotation of said shaft.

2. An ignition control unit for controlling the ignition system of an internal combustion engine comprising; a source of radioactive energy, a switching device responsive to said source of radioactive energy, a shaft adapted to be rotatably driven by an engine, first and second rotor elements carried by said shaft, said rotor elements swinging between said source of radioactive energy and said switching device when said rotor elements are driven by said shaft, said rotor elements having circumferentially spaced openings which permit periodic coupling of said source of radioactive energy and said switching device, means responsive to shaft speed for adjusting at least one of said rotor elements angularly relative to said shaft, and means responsive to shaft speed for adjusting one of said rotor elements relative to the other to adjust the effective opening provided by said rotor elements to thereby determine the angle of rotation of said shaft over which said source of radioactive energy and said switching device are coupled.

References Cited UNITED STATES PATENTS 2,791,724 5/1957 Ekblom et al. 315-4153 2,852,590 9/1958 Fremon.

LAURENCE M. GOODRIDGE, Primary Examiner. I 

